Brick Wall Calculator
Estimate how many bricks, and how much mortar, a wall needs from its size, brick size, mortar joint, openings and wastage.
The formula
Net wall area = length × height − openings. Each brick covers its own face plus half a joint on each side, so the area it occupies is (brick length + joint) × (brick height + joint). Bricks per square meter = 1 ÷ that area, times 2 for a wall two bricks deep. Bricks needed = net area × bricks per m², rounded up, and the order adds the wastage percentage.
Mortar volume = net area × wall thickness − bricks × brick volume. The thickness is the brick depth for a single skin, or two brick depths plus one joint for a double skin. The mortar figure is the wet volume that fills the joints, before any wastage.
Worked example
A wall 5 m long and 2.4 m high is 12 m², and a 2 m² opening leaves a net area of 10 m². With the UK brick (215 × 65 mm face) and a 10 mm joint, each brick occupies 225 × 75 = 16,875 mm², which is 59.3 bricks per m². The wall needs 10 × 59.26 = 592.6, so 593 bricks. With 5% wastage you order 622.2, so 623 bricks. The bricks have a volume of 0.00143 m³ each, so the 10 m² single-skin wall (0.1025 m deep) contains 1.025 m³, of which about 0.176 m³ is mortar.
Brick sizes and the joint
- Choose a preset or enter your own brick length, depth and height. Brick sizes vary by country and make, so check the supplier's figures.
- Brick depth is the thickness of a single skin. In a stretcher bond the bricks lie lengthways and the wall is one brick deep.
- The joint is the mortar thickness between bricks, 10 mm in this calculator unless changed. A thicker joint means fewer bricks per m² and more mortar.
- Unit selection sets the units for the wall size, openings, joint and custom brick fields. Changing it does not convert numbers already typed.
Limits
- It estimates a plain rectangular wall in one bond pattern. Cavity walls, piers, arches, lintels, corners, and bond patterns with headers need extra bricks.
- Double skin means two bricks deep with no cavity, such as a wall built two stretcher courses thick. It counts twice the bricks of a single skin.
- Openings are subtracted as one total area, so enter all doors and windows added together.
- Mortar is only the wet volume that fills the joints. It does not convert to bags of cement and sand, and it does not allow for mortar wastage.
- The brick sizes shown are nominal; check the real size of the brick you buy.
More worked examples
Indian modular brick (190 × 90 × 90 mm) with a 10 mm joint: each brick occupies 200 × 100 mm, so a single skin takes 50.0 bricks per m². A 10 m × 3 m wall (30 m²) needs 1,500 bricks, 1,575 with 5% wastage, and about 0.391 m³ of mortar. Two skins double it to 3,000 bricks, 3,150 with wastage, and 1.083 m³ of mortar.
Imperial with the US modular brick: a wall 20 ft long and 8 ft high with 21 sq ft of openings has a net area of 139.00 sq ft (12.91 m²). With a 0.375 in joint that is 73.8 bricks per m², so 954 bricks, 1,001 with 5% wastage, and 0.218 m³ of mortar.
Custom brick 230 × 110 × 75 mm with a 12 mm joint on an 8 m² wall: 47.5 bricks per m², 380 bricks and 0.159 m³ of mortar.
Joint thickness and wall thickness compared
| 4 m × 2 m wall, UK brick | Bricks per m² | Bricks | Mortar |
|---|---|---|---|
| Single skin, 0 mm joint | 71.6 | 573 | 0.000 m³ |
| Single skin, 10 mm joint | 59.3 | 475 | 0.141 m³ |
| Single skin, 15 mm joint | 54.3 | 435 | 0.197 m³ |
| Double skin, 10 mm joint | 118.5 | 949 | 0.362 m³ |
Errors you may see
- Openings equal to or larger than the wall show "The openings are as large as the wall, so there is nothing to build."
- With the Custom size preset, a missing brick length, depth or height shows "Please fill in the brick length, depth and height."
- A negative joint shows "Please enter valid, positive values." A joint of 0 is accepted, and the mortar then shows as 0.000 m³.
- Bricks are rounded up to whole bricks, both for the wall and for the order with wastage.
Frequently asked questions
How many bricks are in a square meter of wall?
With a UK 215 × 65 mm brick and a 10 mm joint it is about 59 for a single skin, and about 119 for a double skin. Other sizes and joints give different counts, which is why the calculator works it out from your figures.
How much wastage should I allow?
5% is the default. Breakage, cutting around openings and bond patterns with many cuts increase it, and a supplier may recommend more for hand-made or irregular bricks.
Does it work in feet and inches?
Yes. Choose Imperial, enter the wall in feet, the openings in square feet and the joint in inches. The US modular brick preset is built in, or choose Custom and enter the brick in inches.
Why does a thicker mortar joint reduce the brick count?
Each brick takes up its face plus the mortar around it, so a thicker joint spreads the bricks further apart and fewer fit in a square meter.
How many Indian modular bricks for a 10 m × 3 m wall?
With a 10 mm joint and a single skin, 1,500 bricks for the wall and 1,575 to order with the default 5% wastage. A double-skin wall needs twice as many: 3,000 and 3,150.
How much does the joint change the brick count?
A lot, because it applies to both directions. On a 4 m × 2 m wall of UK bricks, a 10 mm joint needs 475 bricks and a 15 mm joint needs 435.
Are the openings entered as one number?
Yes. Add up the areas of all doors and windows and enter the total, in m² or sq ft, to match the units you chose.